1. Field
The present disclosure relates generally to satellites and, in particular, to a method and apparatus for avoiding the illumination of satellites by directed energy sources.
2. Background
Lasers are used for many different purposes. For example, lasers are used as weapons, as a communications medium, and for other types of purposes. For instance, a laser may be directed from a location on the ground or on the ocean toward a target object in the atmosphere or in outer space. This target object may be, for example, a missile or enemy aircraft. In this instance, the laser is configured to damage or destroy the target object. In another example, the target object may be an aircraft, and the laser may be used to establish communications with the aircraft.
In yet another example, a laser beam may be emitted for satellite ranging. In this example, a laser beam may be directed toward a satellite equipped with a reflector. Measurements may be made to identify accuracy of orbit, calibrate radar telemeters, and perform other operations. With these and other uses of lasers, laser beams may inadvertently reach a satellite that is not a desired target object.
Inadvertent illumination of satellites by a laser beam may cause damage to those satellites. Many satellites may carry sensors that are sensitive to the wavelengths used by the laser beam. Illumination of these sensors by the laser beam may reduce the performance of the sensors or may render the sensors inoperative.
As a result, the United States government and other entities have rules and policies regarding the use of lasers that may be pointed towards the sky. For example, an operator of a laser may be required to provide one or more locations in the sky where a laser beam will be emitted, as well as specific times when the laser will be used in these locations. A response is received indicating whether permission is granted for the particular locations and times. This type of emission, however, may require providing the information weeks or days in advance.
Although this type of process may be useful for scientific and other planned activities, obtaining permission in this manner is impractical when the laser beam is emitted from a platform for use in a military mission. Oftentimes, targets may only be known seconds or minutes before the laser is needed. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.